dilatometry

Yet another definition of T uses the kink in dilatometry (a.k.a thermal expansion).

It may be measured by dilatometry if the bulk modulus of the containing fluid is known and ultrasonic methods may also be used (see 5.9 below).

Measurements of bulk modulus can be mae suing the tube method of Arridge & Crowson (1979) or by direct-pressure dilatometry, but these are not commonly done.

Such curves are obtained by dilatometry which is a slow experiment and therefore capable of giving reproducible results for the glass transition temperature which, as we shall see, is strongly time-dependent.